feat: 可配置站点 URL 风格

- 新增 urlStyle 工具与测试：postPath/userPath/sitePagePath 统一生成链接
- 管理端新增 UrlStylePanel 设置面板，settings 服务与 handler 适配
- 全站路由链接与 JSON-LD/sitemap 切换为统一 URL 生成
- middleware 与相关组件适配

frontend/components/home/WorkspaceNav.tsx

@@ -7,6 +7,8 @@ import { Bookmark, Home, ShieldCheck } from "lucide-react";
 import type { BoardWithCount, User } from "@/lib/api";
 import { isStaff } from "@/lib/roles";
 import BoardIcon, { boardColor } from "@/components/BoardIcon";
+import { useUrlStyle } from "@/components/SiteBrandProvider";
+import { userPath } from "@/lib/urlStyle";
 
 // 首页壳内板块切换：仅替换中栏帖子流，不离开工作台
 function boardHref(id: number) {
@@ -23,6 +25,7 @@ export function WorkspaceNavPanel({
   user?: User | null;
 }) {
   const params = useSearchParams();
+  const urlStyle = useUrlStyle();
   const activeBoard = Number(params.get("board")) || 0;
   const showAdmin = !!user && isStaff(user.role);
 
@@ -46,7 +49,7 @@ export function WorkspaceNavPanel({
         </Link>
 
         {user ? (
-          <Link href={`/u/${user.id}?tab=favorites`} className="j13-bcard">
+          <Link href={`${userPath(urlStyle, user.id)}?tab=favorites`} className="j13-bcard">
             <span
               className="j13-bcard-ico"
               style={{ background: "var(--accent-soft)", color: "var(--accent)" }}